1. Field of the Invention
The present invention relates to a light irradiation apparatus and a laser pointer which are provided with a light emitting module as a light emitting element to convert a wavelength of emitting light, and in particular to a light irradiation apparatus and a laser pointer provided with a laser light emitting module using a laser diode. Further, the present invention relates to a lens suitable for use in those light irradiation apparatus and laser pointer.
2. Description of the Related Art
In order to point a reference part in a presentation, a labeler for construction, a marker for apparels, a marker for assemblies and the like, pointers which irradiate a spot light are used. Those pointers have specific characteristics capable of pointing even from a position distant from a pointing object to some extent, because those pointers point at a relevant portion by using light, and also capable of being handled easily, because those pointers are smaller than rod-type pointing apparatuses. In order for a user to point an aimed area regardless of distance to an object irradiated with light, light projected from a pointer needs to be approximately collimated light and laser light is suitable to be used.
Further, in order to point the area aimed by the user and also to improve visibility with respect to the pointed area, laser light emitted from the light source, the diameter of which can be expanded to be irradiated onto a certain area, is required, and a pointer capable of projecting laser light, which is approximately collimated and has an expanded diameter, has been desired.
Thus, in order to project laser light which is approximately collimated and has an expanded diameter, there is required a lens having multiple functions such as expanding the diameter of laser light projected from the light source and making the laser light approximately collimated.
Conventionally, a lens having multiple functions has been formed by combining with high accuracy a plurality of lenses which have individual functions respectively, and a combined lens is well known, in which for example each lens is joined with adhesive or the like while performing a positioning so as to eliminate eccentricity, discrepancy of light axes, and an error in gap of surfaces between the plurality of lenses (refer to, for example, patent reference 1).
[Patent Reference 1]
Japanese Laid-open Patent Application No. 10-123388
However, although complicated and highly precise processing has become possible with the progress in molding technology, there has been a problem that a yield rate becomes low when manufacturing a lens having multiple functions as described above, because there is a case where a positioning error of lenses, that is eccentricity, discrepancy of light axes, and an uneven gap of lens surfaces occur at the time of combining the plurality of lenses which are individually formed.
In addition, in order to improve yield rate, it is possible to increase a positioning accuracy of manufacturing apparatus to combine the plurality of lenses; however, the manufacturing process of combining the plurality of lenses becomes complicated and at the same time, it also leads to an increase in manufacturing cost.
Further, it is also possible to improve a processing accuracy of respective lenses which are combined and to add a mechanism of adjusting the eccentricity, the discrepancy of light axes, the uneven gap of lens surfaces and the like to a lens holder in which those lenses are accommodated, however it causes an increase in manufacturing cost of the lens to be combined, an increase in number of parts, and an increase in processing cost.
Moreover, incident light which enters a combined lens composed of a plurality of lenses is affected by errors caused by the eccentricity, the discrepancy of light axes and the uneven gap of lens surfaces whenever entering respective lenses, and it has been difficult to accurately expand the diameter of incident light to be projected as approximately collimated light.
Accordingly, it is an object of the present invention to provide a lens, in which eccentricity, discrepancy of light axes, uneven gap of lens surfaces, and the like can be reduced without performing the positioning of respective lenses and there is no increase in manufacturing cost of a lens having multiple functions, and to provide a light irradiation apparatus and a laser pointer to which the lens is applied.